Pressure reservoir in rocker shaft for engine brake

ABSTRACT

Disclosured herein are apparatus and methods relating to combustion engines. In an example, a combustion engine includes a head and a rocker assembly. The rocker assembly including: a rocker shaft including therein a pressure reservoir, a pedestal support adapted to be fastened to the head and sized and structured to support the rocker shaft, a rocker lever pivotally supported by the rocker shaft, and a hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate an exhaust valve of the combustion engine.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of the filing date of U.S. Provisional Patent Application No. 63/182,515 (filed Apr. 30, 2021, and entitled “PRESSURE RESERVOIR IN ROCKER SHAFT FOR ENGINE BRAKE”), the complete disclosure of which is expressly incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to combustion engines, and more particularly to combustion engines with engine brakes.

BACKGROUND OF THE DISCLOSURE

Engine brakes in combustion engines utilize the valves and cylinders of the combustion engine to apply forces to the crankshaft which slow the rotation of the crankshaft, thereby “braking” the engine and the vehicle receiving the motoring power from the engine. Engine brakes are commonly used in large diesel engines, for example engines with 15 or more liters of displacement. The Cummins X15™ 15-liter engine, for example, generates more than 400 horsepower with torque ratings of about 1,450-2,050 lb-ft and about 400-600 of braking horsepower. Engine brakes generally comprise a hydraulic circuit that includes a master brake cylinder located in a rocker arm of a rocker assembly which is operably connected to the camshaft and the valves of the engine.

SUMMARY OF CLAIMED EMBODIMENTS

A combustion engine, a rocker assembly, and a method of making the combustion engine with the rocker assembly are disclosed. In some embodiments, the combustion engine includes the rocker assembly which includes a rocker shaft comprising a pressure reservoir; a pedestal support adapted to be fastened to a head of the combustion engine, the pedestal support sized and structured to support the rocker shaft; the rocker lever pivotally supported by the rocker shaft, and the hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate exhaust valves of the engine. The pressure reservoir comprises a reservoir plunger cavity having an inner wall surface and an outer end, a spring, and a reservoir plunger, the spring positioned between the inner wall surface and the outer end and sized and shaped to bias the reservoir plunger toward the inner wall surface in a released state and to allow the reservoir plunger to move toward the outer end in a compressed state. The pressure reservoir is in fluid communication with the hydraulic engine brake mechanism and operable to store fluid under pressure in the compressed state and to release the stored fluid to the hydraulic engine brake mechanism during a transition from the compressed state to the released state responsive to operation of the hydraulic control valve.

In some variations, the combustion engine may have a displacement that is equal to or less than 5.0 liters. The valve cover, attached to the head to enclose the rocker assembly, may have a maximum distance between the rocker lever and the valve cover that is less than 4.0 cm.

In some variations, the pedestal support mounting surface 48 is adjacent the head and opposite the shaft support surface, and a maximum distance from the mounting surface to the valve cover, measured perpendicularly to the mounting surface, is equal to or less than 12.0 cm.

In some variations, the reservoir plunger cavity has a longitudinal axis, the rocker shaft further comprises a fastener cavity and a fluid channel fluidly connecting the fastener cavity and the reservoir plunger cavity, and the fastener cavity extends perpendicularly to the longitudinal axis of the reservoir plunger cavity and is sized and shaped to receive therethrough a fastener adapted to secure the rocker shaft to the head. In some examples, the fluid channel has a longitudinal axis that is parallel to and offset from the longitudinal axis of the longitudinal axis of the reservoir plunger cavity.

In some embodiments, a method of making a combustion engine comprises fastening a pedestal support to a head of the combustion engine; fastening a pressure reservoir inside a rocker lever shaft; securing the rocker lever shaft to the head; and mounting a rocker lever onto the rocker shaft, the rocker lever including a hydraulic engine brake mechanism having a hydraulic control valve configured to selectively actuate exhaust valves of the engine.

In some embodiments, a rocker assembly for a combustion engine includes a rocker shaft comprising a pressure reservoir; a pedestal support adapted to be fastened to a head of the combustion engine and sized and structured to support the rocker shaft; a rocker lever pivotally supported by the rocker shaft; and a hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate exhaust valves of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other disclosed features, the manner of attaining them, and the advantages thereof will become more apparent and will be better understood by reference to the following description of disclosed embodiments taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a sectional view of an engine showing a rocker assembly, a head and a valve cover of an engine;

FIG. 2 is a perspective view of the rocker assembly of FIG. 1;

FIG. 3 is a side view of the rocker assembly of FIG. 1 showing a cross-section of a hydraulic control valve;

FIG. 4 is a cross-sectional view of portions of the rocker assembly of FIG. 1;

FIG. 5 is a cross-sectional view of portions of the rocker assembly of FIG. 1;

FIG. 6 is a cross-sectional view of portions of the rocker assembly of FIG. 1;

FIG. 7 is a cross-sectional view of portions of the rocker assembly of FIG. 1;

FIG. 8 is a perspective view of a portion of the rocker assembly of FIG. 1;

FIG. 9 is a perspective view of a rocker shaft of the rocker assembly of FIG. 1;

FIG. 10 is a cross-sectional view of the rocker shaft of FIG. 9;

FIG. 11 is a cross-sectional view of the rocker shaft of FIG. 9;

FIG. 12 is a cross-sectional view of the rocker shaft of FIG. 9; and

FIG. 13 is a cross-sectional view of the rocker shaft of FIG. 9.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. No limitation of the scope of the invention is intended by the selection of the disclosed embodiments.

Referring to FIG. 1, a combustion engine 20 comprises a head 22 removably mounted on a block (not shown). The block includes combustion chambers and pistons (not shown) moving longitudinally therein and a valve train assembly comprising valves and rocker assemblies 100 (described in detail in FIGS. 2 to 13) configured to actuate the valves, to enable gases to flow into and out of the combustion chambers synchronized by a camshaft (not shown) of the combustion engine 20. Depending on timing and other factors, operation of the valves powers and/or brakes the crankshaft. A valve cover 24 encloses the rocker assembly. The engine 20 may be small enough to fit in personal vehicles, which reduces the space available between the valve cover 24 and the hood of the vehicle, which encloses the engine compartment of the vehicle. In the present embodiment, for example, a distance between the head 22 and the top of the valve cover, indicated by arrow 26, is 120 mm, and a distance between the head 22 and the spring retainer 134, which is the most distal surface of the rocker assembly from the head surface, defining a height of the rocker assembly indicated by arrow 28 and measured orthogonally to the surface of the head 22, is less than 80.13 mm. The short height is possible by the inclusion of the accumulator in the rocker shaft, as described below.

As the foregoing description makes evident, an advantage of the embodiments of the engine 20 described herein is the ability to implement engine braking in small engines, for example engines under 5.0 liters of displacement, and more preferably under 4.0 liters of displacement. It is desirable to implement engine braking mechanisms in small engines. It is therefore desirable to innovate engine brake systems that are suitable for engines with limited space under the hood of the vehicle in which the engine is located. The advantages are possible, in part, by the inclusion of a pressure reservoir in the rocker shaft 200 of the rocker assembly 100.

FIG. 1 also shows a shaft fastener 30 sized and structured to prevent rotation of the rocker shaft 200 and to allow hydraulic fluid, or fluid, to flow through a fastener cavity 46 defined between the shaft fastener 30 and a pedestal support 40 of the rocker assembly 100. A fluid inlet 42 and a fluid outlet 44 establish fluid communication between a fluid source (not shown) and the fastener cavity 46 to permit fluid sourcing and draining. The shaft fastener 30 may be a suitably profiled threaded bolt which connects the rocker shaft 200 and the pedestal support 40 to the head 22. A mounting surface 48 of the pedestal support 40 is adjacent the head 22 surface onto which it is secured by the shaft fastener 30. A hydraulic engine brake mechanism 101 (discussed below) is provided to engage and disengage engine braking with the hydraulic fluid.

Referring now to FIG. 2, the rocker assembly 100 comprises a rocker lever 102 having a body 104, a master piston section 106, a nose section 108, and a lash adjuster section 110. The pedestal support 40 provides a shaft support surface to support the rocker shaft 200, in a known manner. The oil pressure within the rocker lever 102 is preferably maintained to about 4,000 or less PSI, which is accomplished by controlling the sizes of the oil passages in the rocker lever 102. Therefore, the size of the rocker lever 102 cannot be made too small (or the pressure will increase above 4,000 PSI), which therefore leads to reduction in the size of the pedestal support 40 to maintain the small engine design specifications, e.g., valve cover size, and may prevent inclusion of a pressure reservoir in the pedestal support 40.

The body 104 includes a cavity 130 for the rocker shaft 200. The body also includes the fluid passages that operate the master piston, a valve section 132, and the spring retainer 134. The master piston section 106 includes the hydraulic control valve 138, having a plunger 136 (shown in FIG. 3) operating against check ball and spring when acted upon by fluid pressure, in a known manner. The nose section 108 houses a portion of a ball and socket 150 that rests on an elephant's foot 152 of a crosshead 142. The crosshead 142 engages and operates the exhaust valves (not shown) to discharge exhaust gases. Operation of the ball and socket 150 and the crosshead 142 are well known in the art.

The lash adjuster section 110 has a through-hole housing a lash adjuster including a lash adjuster screw 120, a jam nut 124, and a ball 126 providing a pivot point. The ball 126 is pressed upwardly by a pushrod 128 operated by the camshaft of the engine to cause the rocker assembly 100 to pivot.

FIG. 3 is a partial cross-section of the rocker assembly 100 of FIG. 2 showing aspects of the hydraulic engine brake mechanism 101 including the hydraulic control valve 138 including the plunger 136, the spring, and the spring retainer 134, and a master piston 154 operating on the crosshead to actuate one of the two exhaust valves connected with the crosshead 142 when engine braking is engaged. The hydraulic engine brake mechanism 101 also includes the fluid passages (not shown) that fluidly connect the hydraulic control valve 138 with the pressure reservoir. Cross-section AA, BB, and CC are shown in FIGS. 4-6, respectively. FIG. 7 shows an enlarged portion 140 of FIG. 6. Fluid channels 137 and 139 are shown. The channel 137 receives pressurized fluid through a channel 206 (discussed below) and works in conjunction with a pressure reservoir 201 (discussed below) to operate the master piston 154 when engine braking is engaged. The channel 139 receives fluid through a channel 208 (discussed below) and works in conjunction with a solenoid (not shown) that permits or interrupts fluid flow to engage or disengage engine braking, as is known in the art.

Referring now to FIGS. 8-13, as illustrated and described above, the combustion engine 20 comprises a rocker assembly 100 including the rocker shaft 200 comprising a pressure reservoir 201, the pedestal support 40 adapted to be fastened to the head 22 of the combustion engine 20, the pedestal support sized and structured to support the rocker shaft; the rocker lever 102 pivotally supported by the rocker shaft 200, and the hydraulic engine brake mechanism 101 within the rocker lever including the hydraulic control valve 138 configured to selectively actuate exhaust valves of the engine. The pressure reservoir 201 comprises a reservoir plunger cavity 214 having an inner wall surface 216 and an outer end 218, a spring 222, and a reservoir plunger 220, the spring positioned between the inner wall surface and the outer end and sized and shaped to bias the reservoir plunger toward the inner wall surface in a released state and to allow the reservoir plunger to move toward the outer end in a compressed state. The pressure reservoir is in fluid communication with the hydraulic engine brake mechanism 101 and operable to store fluid under pressure in the compressed state and to release the stored fluid to the hydraulic engine brake mechanism during a transition from the compressed state to the released state responsive to operation of the hydraulic control valve.

In some variations, the combustion engine may have a displacement that is equal to or less than 5.0 liters. The valve cover, attached to the head to enclose the rocker assembly, may have a maximum distance between the rocker lever and the valve cover that is less than 4.0 cm. In some variations, the pedestal support mounting surface 48 is adjacent the head and opposite the shaft support surface, and a maximum distance from the mounting surface to the valve cover, measured perpendicularly to the mounting surface, is equal to or less than 12.0 cm.

In some variations, the reservoir plunger cavity has a longitudinal axis 232, the rocker shaft further comprises a fastener cavity 202 and a fluid channel 212 fluidly connecting the fastener cavity and the reservoir plunger cavity, and the fastener cavity extends perpendicularly to the longitudinal axis of the reservoir plunger cavity and is sized and shaped to receive therethrough a fastener 30 adapted to secure the rocker shaft to the head. In some examples, the fluid channel has a longitudinal axis 230 that is parallel to and offset from the longitudinal axis of the longitudinal axis of the reservoir plunger cavity.

The spring 222 may be secured by a washer 224 and a compression washer 226. A channel 206 in the rocker shaft 200 receives fluid from the fluid source which is fluidly coupled via the pedestal support 40 and fluid channels (not shown) therein. The channel 206 is fluidly coupled with the master piston 154 when engine braking is engaged. The fastener cavity 202 is provided to receive a shaft of the shaft fastener 30, which has a head that sits on a surface 204 of the shaft fastener cavity 202. A fluid channel 208 is fluidly coupled with channel 139 to engage or disengage, via hydraulic control valve 138, engine braking, responsive to operation of a solenoid. These channels are best seen in FIG. 10.

Referring to FIG. 13, a plunger cavity 214 houses the spring 222 and a reservoir plunger 220. A channel 212 extends between and fluidly connects the shaft fastener cavity 202 and the plunger cavity 214. The channel 212 has a longitudinal axis 230 which is offset by an offset distance 234 from a longitudinal axis of 232 of the plunger cavity 214. A fluid channel 210 establishes fluid communication between the channel 206 and the fastener cavity 202. The channel 206 is fluidly coupled with the master piston 154 when engine braking is engaged, so that the master piston 154 and a reservoir plunger 220 move in a coordinated fashion to store and release pressure. The offset distance 234 enables placement of the pressure reservoir 201 closer to the top of the rocker shaft 200, where the head of the fastener is located, such that the surface 204 of the shaft fastener cavity 202 lays on a plane that traverses the plunger cavity 214, and this arrangement provides space for the fluid channels in a smaller shaft profile than without the offset.

Plunger 220 may comprise a cylindrical wall sized and shaped to receive the spring 222 and a pressure wall closing one end of cylindrical wall adjacent the fluid channel 212.

As used herein, the transitional term “comprising”, which is synonymous with “including,” or “containing,” is inclusive or open-ended and does not exclude additional, unspecified elements or method steps. By contrast, the transitional term “consisting” is a closed term which does not permit addition of unspecified terms.

While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims. 

We claim:
 1. A combustion engine comprising: a head; and a rocker assembly including: a rocker shaft including therein a pressure reservoir; a pedestal support adapted to be fastened to the head and sized and structured to support the rocker shaft; a rocker lever pivotally supported by the rocker shaft; and a hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate an exhaust valve of the combustion engine.
 2. The combustion engine of claim 1, wherein the pressure reservoir comprises a reservoir plunger cavity having an inner wall surface and an outer end, a spring, and a reservoir plunger, the spring positioned between the inner wall surface and the outer end and sized and shaped to bias the reservoir plunger toward the inner wall surface in a released state and to allow the reservoir plunger to move toward the outer end in a compressed state.
 3. The combustion engine of claim 2, wherein the pressure reservoir is in fluid communication with the hydraulic engine brake mechanism and operable to store fluid under pressure in the compressed state and to release the stored fluid to the hydraulic engine brake mechanism during a transition from the compressed state to the released state responsive to operation of the hydraulic control valve.
 4. The combustion engine of claim 2, wherein the reservoir plunger cavity has a longitudinal axis, the rocker shaft further comprising a fastener cavity and a fluid channel fluidly connecting the fastener cavity and the reservoir plunger cavity, wherein the fastener cavity extends perpendicularly to the longitudinal axis of the reservoir plunger cavity and is sized and shaped to receive therethrough a fastener adapted to secure the rocker shaft to the head.
 5. The combustion engine of claim 4, wherein the fluid channel has a longitudinal axis that is parallel to and offset from the longitudinal axis of the longitudinal axis of the reservoir plunger cavity.
 6. The combustion engine of claim 1, wherein the pedestal support comprises a mounting surface adjacent the head and opposite a shaft support surface, the combustion engine further comprising a valve cover attached to the head to enclose the rocker assembly, wherein a maximum distance from the mounting surface to the valve cover, measured perpendicularly to the mounting surface, is equal to or less than 12.0 cm.
 7. The combustion engine of claim 1, wherein the combustion engine has a displacement that is equal to or less than 5.0 liters.
 8. The combustion engine of claim 7, further comprising a valve cover attached to the head to enclose the rocker assembly, wherein a maximum distance between the rocker lever and the valve cover is less than 4.0 cm.
 9. A method of making a combustion engine, the method comprising: fastening a pedestal support to a head of the combustion engine; fastening a pressure reservoir inside a rocker lever shaft; securing the rocker lever shaft to the head; and mounting a rocker lever onto the rocker lever shaft, the rocker lever including a hydraulic engine brake mechanism having a hydraulic control valve configured to selectively actuate exhaust valves of the combustion engine.
 10. The method of claim 9, wherein the pressure reservoir is in fluid communication with the hydraulic engine brake mechanism and operable to store fluid under pressure in a compressed state and to release the stored fluid to the hydraulic engine brake mechanism during a transition from the compressed state to a released state responsive to operation of the hydraulic control valve.
 11. The method of claim 10, wherein the pressure reservoir comprises a reservoir plunger cavity having an inner wall surface and an outer end, a spring, and a reservoir plunger, the spring positioned between the inner wall surface and the outer end and sized and shaped to bias the reservoir plunger toward the inner wall surface in the released state and to allow the reservoir plunger to move toward the outer end in the compressed state.
 12. The method of claim 11, wherein the rocker lever shaft receives fluid from a fluid source through a first channel.
 13. The method of claim 12, wherein the first channel is fluidly coupled with a master piston when the engine braking is engaged so that the master piston and the reservoir plunger move in a coordinated fashion to store and release pressure.
 14. The method of claim 13, wherein the master piston includes a second fluid channel that is fluidly coupled with a third fluid channel.
 15. The method of claim 14, wherein the second fluid channel is fluidly coupled with the third fluid channel to engage or disengage, via the hydraulic control valve, the engine braking responsive to operation of a solenoid that permits or interrupts fluid flow to engage or disengage the engine braking.
 16. A rocker assembly for a combustion engine, the rocker assembly including: a rocker shaft comprising a pressure reservoir; a pedestal support adapted to be fastened to a head of the combustion engine and sized and structured to support the rocker shaft; a rocker lever pivotally supported by the rocker shaft; and a hydraulic engine brake mechanism within the rocker lever including a hydraulic control valve configured to selectively actuate exhaust valves of the combustion engine.
 17. The rocker assembly of claim 16, wherein the pressure reservoir is in fluid communication with the hydraulic engine brake mechanism and operable to store fluid under pressure in a compressed state and to release the stored fluid to the hydraulic engine brake mechanism during a transition from the compressed state to a released state responsive to operation of the hydraulic control valve.
 18. The rocker assembly of claim 16, wherein the pressure reservoir comprises a reservoir plunger cavity having an inner wall surface and an outer end, a spring, and a reservoir plunger, the spring positioned between the inner wall surface and the outer end and sized and shaped to bias the reservoir plunger toward the inner wall surface in a released state and to allow the reservoir plunger to move toward the outer end in a compressed state.
 19. The rocker assembly of claim 18, wherein the reservoir plunger cavity has a longitudinal axis, the rocker shaft further comprising a fastener cavity and a fluid channel fluidly connecting the fastener cavity and the reservoir plunger cavity, wherein the fastener cavity extends perpendicularly to the longitudinal axis of the reservoir plunger cavity and is sized and shaped to receive therethrough a fastener adapted to secure the rocker shaft to the head.
 20. The rocker assembly of claim 19, wherein the fluid channel has a longitudinal axis that is parallel to and offset from the longitudinal axis of the longitudinal axis of the reservoir plunger cavity. 